Eskişehir Technical University Journal of Science and Technology A - Applied Sciences and Engineering

Eskişehir Technical University Journal of Science and Technology A - Applied Sciences and Engineering Kapağı
Yayıncı
Eskişehir Teknik Üniversitesi
e-ISSN
2667-4211
Başlangıç Yılı
2017
Dil
İngilizce
Durumu
Aktif
Dizin
Havacılık Dizini, TRDizin
Yayın Aralığı
Aylık

Son Sayı (Latest Issue) - Year 2022 Volume 23 Issue 3

Abstract (Özet)

Many reinforced concrete structures are built side by side in our cities. There are very few applications of earthquake joints in adjacent apartment buildings, most of them were constructed completely adjacent. Adjoining buildings or any property should be protected from damage or collapse during construction, restoration and demolition work. In case of the static condition, protection must be supplied for foundations, walls and roofs. We have already observed many building collapses in Turkey with a great number of life lost. For the constructed buildings, there is a need to understand the structural system of an existing building to manage risk. In case of earthquakes like dynamic loading, earthquake joints are essential. The Turkish Building Earthquake Code (TBEC) 2018 requires calculations of vertical joints for some types of structures. Earthquake joints should be left in the gap calculated for structures of some height. It is thought that this gap will prevent the structures from colliding. However, it has been the subject of research how the performance of the building will change when it is produced adjacent or when floor offsets cause collisions at earthquake joints. In this study, structures of different heights were analyzed in the time domain for specific earthquake motions. Collision situations of more than two buildings are discussed by making a street model. Structural performances of discrete and adjacent structures obtained from nonlinear analysis were compared. The motion parameters obtained from the structures were analyzed in the time-frequency domain by wavelet and Hilbert transforms. To determine the effects of earthquake joints, condition assessment and damage detection studies were carried out and the sufficiency of seismic joints was discussed.

Abstract (Özet)

Compared to commonly use carbonaceous materials such as carbon nanotubes or graphene nanoplatelets, hydrothermal carbons (HTCs) are obtained with environmentally friendly approaches at a lower cost. Although HTCs have a wide application area such as batteries, magnetic materials, supercapacitors, adsorbent materials, etc., there are few studies on the usage of HTC as reinforcement material for composites. In this study, polyethylene matrix composites containing different amounts (0.5 wt.%, 1 wt.%, 2 wt.%) of HTCs were fabricated via the injection molding process. The effect of HTCs content on the wear properties of polyethylene matrix composites was investigated. Reciprocating wear tests were performed applying different loads at dry sliding conditions. To correlate with wear results, the mechanical properties of samples were determined by tensile and impact tests. Also, FTIR and DTA analyzes were conducted to understand the effect of HTCs on the structural and thermal properties of composites. Results show that the addition of HTCs led to the enhancement of mechanical and tribological properties of polyethylene at lower amount reinforcement ratios. Thus, it can be said that HTCs could be alternative carbonaceous reinforcement material for polymer matrix composites.

Abstract (Özet)

İki boyutlu (2B) malzemeler, bu malzemelerin ürettiği cihazların yüksek performans göstermesi nedeniyle birçok araştırmacının ilgisini çekmiştir. 2B malzeme elde etmek için solüsyon tabanlı kimyasal sentez, kimyasal buhar biriktirme (KBB), moleküler ışın epitaksisi, atomik katman biriktirme, darbeli lazer biriktirme (DLB) gibi işlemler sırasında saatler gerektiren farklı üretim yöntemleri bulunmaktadır. 2B yapılar elde edildikten sonra, kusurları da dahil olmak üzere özellikleri farklı karakterizasyon araçları ile ortaya çıkarılmalıdır. Karakterizasyon süreci de üretim süreci gibi zaman ve uzmanlık gerektirir. Bu açıdan, üretilen örneklerin pratik ve hızlı sınıflandırılması için Evrişimli Sinir Ağları (ESA) gibi derin öğrenme yöntemleri bir çözüm olabilir. Ancak, yukarıda bahsedilen uzun deneysel süreçler nedeniyle araştırma laboratuvarlarının çoğunda yeterli sayıda örnek bulunmamaktadır. Bu çalışmada, farklı elektronik uygulamalarda yüksek potansiyele sahip, yaygın olarak çalışılan bir 2B yarı iletken olan MoS2'nin yapay olarak oluşturulmuş görüntülerini kullanan bir CNN algoritmasının performansı sunulmaktadır. Normal ve kusurlu MoS2 pullarını içeren sentetik optik mikroskobik görüntüler, Fresnel Denklemleri kullanılarak farklı malzemeler üzerine gelen ışığın yoğunlukları ile oluşturulur. Normal ve kusurlu örnekleri tespit etmek için derin bir CNN algoritması oluşturulmuştur. Doğruluk ölçümlerinin sonuçları, CNN'nin gelecekte yeterli sayıda gerçek görüntü ile iki boyutlu malzemelerin karakterizasyonu için kullanılabileceğini göstermiştir.

Abstract (Özet)

In this paper, we have studied monolithic diode-pumped Tm-doped fiber laser to be used as a pump source for Ho-YAG systems. The cavity is designed to achieve high optical-to-optical efficiency and robustness against amplified spontaneous emission (ASE) induced parasitic lasing via optimizing the doped fiber length and cavity parameters. Experimentally, we have demonstrated 1907.7 nm fiber laser with an output power of 79 W from 10/130 μm Tm-doped double clad fiber, enabling high brightness and radiance density as well. The laser cavity has a slope efficiency of ~55%, ASE suppression of > 40 dB and a near-diffraction-limited beam quality of M2~1.07.